THE fundamental defect in Duchenne muscular dystrophy is obscure. Early investigators attributed the disorder to a primary defect of the skeletal muscle itself,1 but alternative suggestions have implicated the motor neurone2,3 or the vascular supply4. Recent attention has been directed to the plasma membrane of muscle as well as of other tissues. Several authors have postulated a generalised membrane defect as the fundamental problem in this disorder5-7. © 1975 Nature Publishing Group.